Why am I not able to move some bones?
A bone is defined by two points, known as the head and tail of the bone. When you select one of these points you only move that point, the bone/s defined by that point then stretch to fit the opposite point.



If you want to move both points of a bone together you select both points. Clicking the body of the bone will select both points for you.



While I don't think it applies to you, you can lock the points of a bone in the bone transform properties, so that they can't be moved in edit mode. If this is the case, it is a matter of turning off the lock.